Apparatus for gasifying finely divided granular fuel



A. ROZENEK I 2,222,044

APPARATUS FOR GASIFYING FINELY DIVIDED GRANULAR FUEL Nov. 19, 1940.

. 2a, 1937 :5 Sheets-Sheet 1 Filed Sept INVENTOR A. ROZINEK Nov. 19, 1940.

ATIARATUS FOR GASIFYING FINELY DIVIDED GRANULAR FUEL Filed Sept. 23,

1937 3 Sheets-Sheet 2 Fig. 2a

' 44 F/ Qb \NVENTOR A. ROZINEK 4 ,144. 8) 0 f ATTVSA Nov. 19, 1940. A. R'OZINEK 2 2,222,044

APPARATUS FOR GASIFYING FINELY DIVIDED GRANULAR FUEL Filed Sept. 28, 1937 3 Sheets-Sheet 3 INVENT'QR A RTH UR Roz: NEK

' ATTY Patented Nov. 19, 1940 UNITED STATES APPARATUS FOR GASIFYING FINELY m VIDED GRANULAR FUEL Arthur Rozinek, Budapest, Hungary, assignor of one-half to Gza Szikla, Budapest, Hungary Application September 28, 1937., Serial No. 166,190 In Germany October 7, 1936 10 Claims.- (01. 48-76) the gasifylng shaft, likewise, will reach the bot- In order to enable finely granular fuel, e. g. coal dust of a grain size up to mm., to be gasified partly or entirely in a state of suspension, such gasification being effected e. g. according to 5 the prior Patent No. 2,099,968 it is indispensable that such gasification should take place in' a rising current of air and/or gas, and that the molten slag should be discharged in a liquid or pasty condition continuously and in an undisturbed manner.

Thereby the following difiiculties arise:

It is difiicult to attain uniformity of temperature over the whole volume of the 'gasifying chamber. It is a well-known fact that even in the fire chamber above a travelling grate the composition of the gas as well as the distribution of temperature will present a striking lack of uniformity. Gasification of fuel held in a state of suspension, will, due to the velocity of reaction of the process of gasification, show a still greater tendency in the direction of such lack of uniformity than shown by ordinary combustion on a grate. It is only in an inadequate extent that the defined air jet of large cross-sectional area entering at the bottom of the gasifying chamber will be permeated by the particles of coal held in suspension. Moreover, when the air slide is adjusted to different positions, the shape of the air jet will also become altered, in consequence whereof the gas flow in the gasifying chamber, the thoroughness of mixture with the fuel and the formation of eddies will all become altered to such an extent as to cause the gasifying process to take place in a different manner at difier- 35 ent loads. In case the opening through which the air is blown into the gasifying chamber is of large dimensions, the fuel in suspension will show a tendency to agglomerate and, accordingly, to drop through the bottom opening, while on the other hand the undivided air jet'will reach a great height in the gasifying chamber and will give rise to narrow flames in the upper regions of such chamber. As a result thereof, the gas conditions and temperatures will be widely divergent within the gasifying chamber, and, moreover, free oxygen will get into the upper regions of the chamber and will cause excessive local temperatures of detrimental effect.

- The removal of the molten slag accumulating on the bottom of the gasifying chamber presents considerable dill lties. Around the bottom opening a crater of coke will be formed on the slopes of which the slag pouring down in theform of drops will fall, and it is over these slopes that the slag flowing down along the walls of tom opening. At the border of this opening the jet of cold air will impinge on the slag, which latter will solidify, clog the bottom opening and finally close the latter entirely. The more narrow the opening, the greater will be the tendency towards the formation of slag. To remove the liquid or pasty slag in a proper manner and to keep the opening free is a most difficult task. The various well known arrangements for the removal of liquid slag fro'm smelting chamber furnaces and tapping generators are of a fundamentally different nature, as there the introduction of air and the removal of the liquid slag do not take place through the same opening, but through different openings separated from each other.

In developing such a process of gasifying fuel held in suspension it has now been found that it is possible to avoid all these drawbacks, if a sufficiently high temperature, ensuring the necessary high velocity of reaction of the gasification and the easy meltingof the slag is obtained uniformly over the whole interior volume of the gasifying chamber. At the same time the efiicient removal, without any trouble, of the flowing slag can-be assured. For this purpose the bottom opening and the parts adjacent thereto are constructed as disclosed in the following description.

The accompanying drawings show merely by way of example a double-chamber generator according to the invention.

Fig. 1 is a vertical section,

Figs. 2a and 21), respectively, are horizontal sections H and b-b of Fig. 1.

Fig. 3 is a vertical section along the lines cc of Fig. 1.-

Fig. 4 is a detail view of another embodiment of the air current distributor.

Fig. 5 is a detail view of another embodiment of the invention.

l is the gasifying chamber operating with a rising current of air and/or gas and 2 is the gas discharge chamber joining on to the said gasifying chamber and conducting downward the flow of gaseous products of reaction.

Finely divided granular fuel 4!, e. g. coal dust, is fed by pipe 40 into a hopper in the vicinity of the top of the gasifying chamber. Through the bottom opening of the hopper, regulated by av slide 39, the coal dust is fed to the catapult 38, throwing the coal dust in the gasifying chamber I.

The coal dust may alternatively be introduced from above through pipe 46, hopper 45, slide M ing from the pressure chamber 6 into the gasifying chamber and is gasified in a state of suspension. The design of such a generator known per se is, according to the invention, further developed in the following manner:

Above the bottom I of the gasifying chamber an intermediate bottom 8 is arranged, in which an opening 9 is provided above the bottom opening 5. Preferably the intermediate bottom is arranged longitudinally as shown in Fig. 1; it

may, however, incline under an angle which is smaller than the natural angle of slope of the mixture of coke and slag accumulating on it. Accordingly, such mixture forms a collecting funnel or craterby which the liquid .slag is conducted towards the opening of the funnel. Such a crater composed of a mixture of coke and slag is insensitive against the slag running off as well as against the high temperature, whereas materials of construction even of the most high-grade kind would hardly prove resistant at this place. The intermediate bottom referred to divides the gasifying chamber i into two chambers, of which the upper more voluminous one serves as a slag melting chamber, whilst the lower one I serves as a mixing chamber. From the slag melting chamber the slag flows towards the edges l2 situated in a zone of high temperature, from which edges it will then drip down. Over such edges of the opening provided in the bottom of the chamber as are exposed to the danger of becoming clogged by slag, as for instance II, the edges l2 of the bottom opening of the intermediate bottom project (Fig. 3) so that'the slag will drip ofi from the edge of the upper opening into the free bottom opening.

In. the mixing chamber I0 itself no liquid or pasty slag is formed, as the temperature in the mixing chamber is, owing to the air entering into the same, only suflicient, at most, for the sintering but not for the melting of the ashes into which the fuel particles are converted at this place. Moreover, as a consequence of the separation efiected by the upwardly flowing current of air and/or gas it is preponderantly only fuel particles of larger size, burnt out to a small ex-- tent only, that are present in the mixing chamher. With the progress of burning out, the particles are reduced in size, are carried upward by the current of gas and are consumed in the melting chamber so as to leave only their remnant of ashes. It is here, accordingly, that the preponderating proportion of ashes is obtained, the

fine particles of such ashes become molten, co-

agulate into lumps of larger size and descend or run down along the wall to the bottom opening. The opening of the intermediate bottom should be made sufllciently large to enable the larger particles of fuel to drop down into the mixing chamber against the rising current of gas. In order to enable the intermediate bottom, the

drip edge and the mixing chamber to exercise the effect for which they are intended, it is indispensable that, in order to avoid any integral full air jet, the bottom opening 5 should be subdivided into a number of part openings l4 fitted with separate throttling'members IS, the current of air being thereby divided into individual jets each of which possesses a velocity at the gap cross-sections preventing any falling through of the particles of fuel.

The liquidor pasty slag dropping down from the gasifying shaft and particularly from the drip edges, failing a free opening, will not be able to simply drop out, but will fall on the air current distributoronly a small portion of such sla dropping through the gaps of this distributorand it is accordingly necessary to remove it. At the same time it is necessary to avoid any clogging of the free gap cross-section by solidifying slag. For this purpose the gaps serving as openings for the, introduction of the airblast are arranged along a belt, and the surface thus fitted with gaps or slots is moved along below the bottom opening of the gasifying chamber. By means of the arrangement to be described below of the air blast distributor the difliicult task of separating the liquid or pasty slag resulting from the finely granular fuel and removing the said slag so as to prevent any clogging by slag of the air inlet openings has been successfully solved;

In the drawings the bottom opening 5 of the gasifying chamber is shown by way of example subdivided into a number of openings (parallel gaps or slots) distributed uniformly over the whole cross-section of the said opening. The slots i 4 are arranged in the cylindrical surface of the hollow cylinder l6 rotatable around its axle I1. On the slots l4 throttling members I5 are provided, which latter are composed of parallel bars forming a cage-like cylinder is rotatable around the axle l8. A driving means not shown on the drawings preferably keeps the slotted drum in permanent rotation in the direction of the arrow 20, in consequence whereof the said drum carries along the throttling cylinder I9 engaging in the manner of a tooth into the slots H or, the throttling cylinder l9 may be driven and carry along the extemalcylinder IS. The regulation 'of the free throughflow crosssection of the slots I4 provided in the bottom opening 5 is effected by the adjustment of the throttling members i5, such adjustment being effected by tangential or by radial displacement of the throttling cylinder l9. Inthe first case the axle of rotation l8 of the throttling cylinder I9 is displaced in the sense of arrow 2| or in an opposite direction that means along the periphery of cylinder l6, whereby some of the slots i 4 of the hollow cylinder l6 arranged under the bottom opening 4 are cleared. By adjusting on the other 'hand the axle i8 of the throttling cylinder IS in a radial direction the bars ii of the throttling cylinder l9 penetrate less or more in the slots l4 of the hollow cylinder l6. Inboth cases the slots i4 lying under the bottom open-- -ing become less or more closed.

By means of this arrangement, proper distribution of the air entering the gasifying shaft is obtained at all loads. In order to enable greater quantities of slag to be removed, some of the bars l5 serving as throttling members,-- I A for instance, as represented on the drawings. every fourth bar 22-may be of greater height and may act as a milling edge. The throttling cylinder will, owing to its engagement into the slots I4,

, squeeze out any slag which may be contained in scraper 23 removes such slag as may possibly adhere to the periphery. a), W A lateral wall of the mixing mber, preferably the one situated at the place of discharge of the air blast distributor drum, is removable, for instance, in the embodiment shown by way of, example, capable of being tilted upward, so that the chamber and the opening of the intermediate bottom can, after tilting up the wall ,be inspected through an inspection'hole 25 provided in the wall of the air blast chamber, and cleaned, if necessary, of any slag which may be adhering to it. The front wall capable of being tilted up is preferably held in its position by a weight 26 or by a spring load and will be pushed aside by 2 any pieces of slag or larger size or by any firebricks which might possibly have dropped down.

Another method for enabling the mixing chamber to be inspected and cleaned might con-' sist, for instance, in making provision for the swinging aside, for instance supported on two lever arms, of the air blast distributor drum.-

As already explained this air blast distributor and slag removing apparatus has'nothing' in common with the well-known travelling furnace grates. A travelling furnace grate acts as a. support for the fuel until the latter has entirely or almost entirely become burnt to ashes and such a grate has accordingly to be moved at' a slowspeed over a long path of combustion in order to oifersufiicient time,'corresponding to the size of the lumps of the fuel, for the cominvention is moved below an opening of relatively narrow width. The air entering through the slots carries the fine granular fuel upwards and separates the latter from the liquid or pasty slag which has not been produced on the grate by combustion, but has been formed in the gasifying pit and drops down on thedrum from above, mainly from the drip edges, the said slag accumulating in larger drops or lumps which moreover are of much greater specific weight than the fuel and are discharged fying shaft in due course.

The velocity of motion of the distributor is determined by the task of removing the slag and keeping the air slots freeof any slag. It should be noted in this connection that in view of the narrow bottom opening this velocity, particularly in the case of coals containing a high proportion of slag, is considerable, in any case much greater than the usual velocity of burning fuel on a travelling grate. Accordingly the velocity of the motion of the distributor is exclusively a function of the quantity of slag formed per unit of time, while at the same time the velocity should be adapted to the highest load and preferably also to the highest percentage of ash contents of the various fuels to beemployed, seeing that a higher velocity does not represent anydraw-back for coals possessing a lower percentage of ashes. It is by this circumstance that from the gasithis memberserving as a distributor of air blast and as a removing mechanism for liquid or pasty her l3 by means or the slides a through opening 4 to the mixing chamber l0 above the bottom I to the opening 5, i. e. to the rising jet of air, a

while at the sametime the slag dropping on the stream of coke is carried along, and the stream of coke removes the slag on the path covered by the said stream and exerting a cleaning effect onthe edge 21 of the opening.

Methpd of operation jet and thereby intense mixing of these particles with the air. This process of mixing is still more advanced by the intense formation of eddies in the mixing chamber, Practical tests have shown that by means of the arrangements enumerated, that is, by the subdivision of the air jet and by the employment of the mixing chamber, it is possible, even in the case of a condition of pure suspension, to consume a large part of the oxygen of the air already in the mixing chamber, so that at'the various loads the oxygen still existing ,in the slag melting chamber is rapidly consumed and following this an efficient gasification of the particles of coke is obtained. In consequence thereof a sufiiciently high temperature is available within the bottom opening 9 to ensure that the slag should not solidify, .but should drip down from the edges I2, any clogging of this 'opening by slag being thus avoided. As already mentioned, these edges I2 are on those sides where this is necessary (in the assumed case on three sides) projecting over the edge ll of the bottom opening 5, so that-the slag will drop on the rotating air blast distributor drum l6 and will be discharged. In this manner the edges of the bottom opening are kept free of any slag.

preferably of the latter and of the air blast distributor drum.

It is only by'the described cooperation of both parts that it has been possible to obtain operation ensuring uniform gasification, safe melting and undisturbed removal of the liquid or pasty slag, while avoiding all possibility of local clogging by slag.

In the embodiment shown by way of example it is through the slides 3 and throughthe connecting passage that the incandescent coke passes into the mixing chamber whence it is forwarded to the bottom opening 5. This stream of coke which, by suitably constructing the lateral walls 29 'of the mixing chamber canialso be conducted to the two narrow sides ll (Fig. 2, section bb) of the-bottom opening 5, is within therange of its new exerting a cleaning action, 1. e. it carries away any slag which may-become formed or which may drop down from above. For this reason it is possible, within the range of this -moved stream of coke, to dispense entirely=orpartly with the screening effect of the intermediate bottom, i. e. the edges of the latter need not project over the edges of the bottom opening,

as indicated on Fig. 1 by placing the drop pipe 28 in a receded position relatively to the edge 21.

It should be noted, however, that it is not permissible that liquid slag should drop on this streamof coke in such quantities as to causethe latter to be soaked by the slag and rendered pasty thereby, as in this case the stream of coke would no longer continue its uniform motion and would get into the range of the opening in lumps and fragments as soon as it has lost its crumbling structure.

In the upper part-of .the gasifying chamber 1,

i. e. in the slag melting chamber the coke pro-' duced from the fuel particles is gasified, whilst the remanent incombustible part will melt,. coagulate and drop down or become precipitated on the walls. Any particles of fuelwhich might possibly be adhering'to the lumps of slag during the coagulation of the latter will during the descent of these lumps and their rolling down over the crater slope of the intermediate bottom find time for becoming completely burnt out,

particularly as .they are passing into gas zones of constantly increasing activity and finally get into regions where free oxygen is available.

small particles continues to take place until larger-sized lumps of well burnt-out slag are as air blast distributor, it is also possible to employ other members constructed in a correspondingly similar manner on the bottom opening, for instance a drum, the cylindrical surface of which is composed of vanes, in accordance with Fig. 4,

and only small gaps which are adjustable, as required, are left free within the opening by the said vanes, while on the further circumference the vanes are turned to present larger. openings. The vanes 3| are pivoted on the drum and are movable with their free ends engaged in a fixed guide path 32 acting as a cam as long as they are in the vicinity of the bottom opening, but as soon as they move away from the latter they topple over and hang down freely, tot-be again restored by the guide 32 into the operative position.

Instead of the drum it would, as already pointed out above, also be posible to provide a belt capable of being moved in the horizontal direction, which belt cooperates with throttling members of a similar kind. Fig. shows such a construction having aniendless link chain 33, which correcarrier 35 running on the drums 36 and the endless chain 33 whereby the rods penetrate more or less in the corresponding air inlet slots 31.

Above 35; the air blast distributor, also, the coagulation of In Fig. '5, the corresponding parts of the device are indicated by the same reference characters as in Fig. 1. In the case of an actually constructed plant, the dimensions of the bottom opening 5 are: width 350 mm., length 700 mm.; those of the bottom opening 9 are: length 600 mm., with drip. edge on three sides; the slot width I in the air blast distributor is -15 mm., the total area of the slot openings amounts to about 400 cmfi the free height of the mixing chamber to 300 mm. and that of the gasifying chamber to 3500 mm., while the dimensions of the bottom of the latter are 1600 by 1800 mm. This plant is capable of gasifying 2.5 tons per hour of brown coal having a net calorific value of 5300 calories per kg., but it should be noted in connection with this figure that it is only by the output capacity of the boiler that the'load of the gasifying chamber was limited and that it could most probably be increased still further. The same final capacity can also be obtained with low-grade coals, i. e. in the same proportion in which the calorific value of the fuel is lower, the quantity of fuel which it is possible to gasify in this apparatus can be increased.

What I claim is:

1. An apparatus for gasifying finely divided granular fuel, comprising a gasifying chamber having a bottom opening, means for introducing air for gasification of the fuel through said opening, a cylindrical drum mounted beneath said opening with its cylindrical surface closing the latter, said drum being provided with axially extending slots for dividing the airfiowing through said opening into a plurality of jets, and a fimnelshaped interr'nediate nozzle bottom provided with an opening-and-positioned above said bottom opening in the range of high temperatures, said intermediate bottom having edges projecting beyond the edges of the bottom opening to insure that slag in a liquid or pasty condition will drip from the edges of the intermediate bottom directly onto the drum. r

2. An apparatus for gasifying finely .divided granular fuel, comprising a gasifying chamber having a bottom opening, means for introducing air for gasification of the fuel through said opening, a cylindricaldrum mounted beneath said opening with its cylindrical surface closing the latter, said drum being provided with axially extending slots for dividing the air flowing through said opening into a plurality of jets, a funnelshaped intermediate nozzle bottom provided with an opening and positioned above said bottom opening in the range of high temperatures, said intermediate bottom having edges projecting beyond the edges of the bottom opening to insure that slag in a liquid or pasty condition will drip from the edges of the intermediate bottom directly onto the drum, and an internal cage-like drum of smaller diametermounted within said drum, said inner drum having longitudinally extending bars adapted toenter into the slots of the outer drum similarly to the meshing of gears in the vicinity of the bottom opening to partly close the slots in the outer drum. 3. An apparatus for gasifying finely divided. granular fuel, comprising a gasifying chamber having a bottom opening, means for introducing air for gasification of the fuel through said opening, a cylindrical drum mounted beneath said opening with its cylindrical surface closing-the latter, said drum being provided with axially extending slots for dividing the air flowing through said opening into a plurality of jets, a funnelwidth 400 mm.,

shaped intermediate nozzle bottom provided with an opening and positioned above said bottom opening in the range of high temperatures, said intermediate bottom having edges projecting be- 5 yond the edges of the bottom opening to insure that slag in a liquid or pasty condition will drip from the edges of the intermediate bottom directly onto the drum, an internal cage-like drum of smaller diameter mounted within said drum,

said inner drum having longitudinally extending bars adapted to enter into the slots of the outer drum similarly to the meshing of gears in the vicinity of the bottom opening to partly close the slots in the outer drums, and means for adjusting the position of the axis of the inner drum about the axis of the outer drum to vary the position of the zone of engagement between said drums.

4. An apparatus for gasifying finely divided granular fuel, comprising a gasifying chamber having a bottom opening, means for introducing air for gasiiication of the fuel through said opening, a cylindrical drum mounted beneath said opening with its cylindrical surface closing the latter, said drum being provided with axially extending slots for dividing the air flowing through said opening into a plurality of jets, a funnel-shaped intermediate nozzle bottom provided with an opening and positioned above said 0 bottom opening in the range of high temperatures, said intermediate bottom having edges projecting beyond the edges of the bottom opening to insure that slag in a liquid or pasty condition will drip from the edges of the intermediate 35 bottom directly onto thedrum, an internal cagelike drum of smaller diameter mounted within said drum, said inner'drum having longitudinally extending bars adapted to enter into the slots of the outer drum similarly to the meshing of gears in in the vicinity of the bottom opening to partly close the slots in the outer drum, and means for radially adjusting the position of the inner drum relatively to the outer drum to vary the extent of w the air gaps in the bottom of the gasifying chamber.

5. An apparatus for gasifying finely divided granular fuel wholly or partly in suspension, comprising a gasifying chamber having a-bottom opening through which air for gasification of the 0 fuel is introduced, an intermediate bottom provided with an opening and positioned above said bottom opening in the range of high temperatures, said intermediate bottom having dripedges projecting beyond the edges of the bottom opening to insure that slag in a liquid or pasty condition will drip from said edges, and a movable 5 air current distributor closing the bottom opening and having apertures for the passage of the air, said distributor serving as means for removing the slag falling from said drip edges in a liquid or pasty condition, and by the action of the 10 air currents to prevent particles of fuel from falling through the apertures.

6. An apparatus for gasifying finely divided granular fuel, comprising a gasifying chamber having a bottom opening, means for introducing 1 air for gasification of the fuel through said opening, a belt mounted beneath said opening to close the latter, said belt being provided with transverse slots for dividing the air flowing through said opening into a plurality of jets, a fun- 20 nel-shaped intermediate nozzle bottom provided with an opening and positioned above said bottom opening in the range of high temperatures, said intermediate bottom having edges projecting beyond the edges of the bottom opening to insure 25 that slag in a liquid or pasty condition will drip from the edges of the intermediate bottom directly onto the belt, and means for throttling the openings in said belt.

7. An apparatus according to claim 5, in which the intermediate bottom is substantially horizontal and is adapted to retain with a natural angle of repose a deposit of mixed fuel and slag forming a collecting funnel for liquid slag.

8. An apparatus according to claim, Lin which tubes for the passage of a cooling medium are arranged on the edges of the opening of the intermediate bottom, said tubes defining the drip edges. r

9. An apparatus according to claim 1, in which (0 the drip edges of the opening in the intermediate bottom are retracted relatively to the edges of the underlying bottom opening.

10. An pparatus according to claim 1, in which a lateral wall portion of the chamber between the bottom opening and the intermediate bottom is pivotally mounted to form a closure for said opening and in which means are provided for moving said wall portion. 

